Efficieny of an Engine

Hello, I would like help with analyzing the car engine for a deeper understanding.

This is what I cant understand in my head.

A piston is connect to a rotating circular with a radius of 0.10m and mass of 1kg. If you pushed the piston down 0.20 m with a force of say 100 N (thus work = 20 J). This would cause the rotating circle to make a half turn. This seems inefficient, is it? Could someone explain if there is an energy loss here, and if so where did the energy go?